Figure 4. Outward (Reverse) Proton Current through Udorn M2.

The difference in currents indicated by “A” and “B” in Figure 3 is plotted as a function of applied voltage. Current-voltage relationships were measured with 2 s long ramps (from −60 to + 80 mV; A, 30 s before acidification; B, 10 s after acidification). Note that the larger outward currents seen in the current-voltage relationships of these Udorn M2 mutants agree with the presence of outward current in Figure 3.